Grid forming apparatus



5 H. A. sNoW GRID FORMING APPARATUS Filed April 28, 1951 Patented Aug.30, 1932 and rice HAROLD A. SNOW, OFBOONTOFT, NEN J'ERSEY, ASSIGNOR, BYMESNE ASSIGNMENTS, TO

f BADIOCORTSORATION OF AMERICA, OF NEW YORK, N. Y., A CORPORATION OFDELA- WARE earn FORMING APPARATUS Application filed April 28,

to impart difierent operating characteristics to difierent parts of thegrid structure. As described'in the'copending application of StuartBallantine, SenNo. 544,801, filed June 16, 1931, grid electrodes forpoly-mu tubes may be formed by first preparing a helical grid winding,usually of uniform pitch throughout its length, and then axiallydisplacing some of the turns of the winding to vary the spacing ofadjacent turns.

Objects of the present invention are to provide a simple and effectiveapparatus for holding and bending the grid winding. A further object isto provide bending apparatus including a guide for accuratelypositioning the grid blank with respect to the path of movement of thebending members. More specifically, an object is to provide bendingapparatus including clamping arms for holding a grid blank, one of thearms carrying a guide rib which enters between adjacent turns of thegrid winding to position the same, and spreader rods supported formovement through and diametrically of the grid for effecting an axialdisplacement of portions of the grid winding.

These and other objects of the invention will be apparent from thefollowing specification, when taken with the accompanying drawing, inwhich,

Fig. 1 is a side elevation of one embodiment of the invention, withparts in section as viewed on line 11 of Fig. 2,

Fig. 2 is a plan view of the same, with parts broken away,

Fig. 3 is a longitudinal section on line 33 of Fig. 2,

Fig. 4 is a fragmentary front elevation showing a gauging device mountedon the apparatus, and

Fig. 5 is an elevation of a reshaped grid.

In the drawing, the reference numeral 1 identifies a supporting standwhich carries a clamping arm 2 and to'which is pivoted the movableclamping arm 3. The opposed faces of the clamping arms are provided withsemicylindrical recesses 4 that cooperate to pro- 1931. Serial No.533,508.

vide a cylindrical chamber for recessing a grid blank in the form of ahelical winding 5 secured to and supported by one or more longitudinalwires 6.

The clamping arms 2, 3 are provided with :3

alined apertures 7, 8, respectively, whose axes extend substantiallydiametrically of the axis of the cylindrical chamber provided by therecesses 4. The lower ends of spreader rods 9 are adjustably mounted ina cross head 10, being locked therein by set screws 11, and the upperpointed ends of the spread er rods are normally retained below thebottom of the recess 4 in clamping arm 2 by the spring 12 which urgesthe crosshead 10 downwardly into contact with the stop 13.

The upper clamping arm 3 is normally held in raised position by a spring14, and lugs 15, 16 project forwardly from clamping arm 2 and crosshead10, res ectively. To insure that the helical grid blank will be sopositioned that the pointed ends of spreader rods 9 will pass betweenturns of the grid winding, a narrow rib or guide 17 projects into therecess 4 of the lower clamping arm 2.

In reshaping a helical grid blank, the operator places the blank in therecess 4 of the lower clamping arm, and with the guide 17 enteringbetween adjacent turns at the central portion of the winding 5. Theupper clamping arm 3is depressed to hold the grid blank in place, andthe crosshead 10 is raised to force the spreader rods diametricallythrough the grid winding. In practice, these operations are performed inproper sequence by pressing lugs 15,16 towards each other with the thumband a finger of one hand. Upon releasing the pressure, the spreader rodsare withdrawn by spring 12 and the arm 3 is lifted by spring 14. Thereshaped grid may then be lifted from the arm 2.

As shown in Fig. 5, the finished grid has portions of the winding 5displaced axially to form apertures, indicated at A, A, which are, incomparison to the average spacing between turns, of relatively largesize. Due to the positioning of the grid blanks by the guide 17 which isclose to the path of movement of the spreader :rods, the finished gridsare very uniform as to their electrical prop.-

erties. The apertures A formed in the heli cal winding are substantiallyidentical as to size and shape, and these factors determine theoperating characteristics of the finished grid even though there may besome slight variationin the relative axial location of the apertures indifferent grids.

Ordinary care in fitting the approximate.

center of the grid winding over the guide 17 will insure a substantiallyuniform output,

- but a" gauge may be provided'to assist the operator in placing thegrid blanks in proper position inthe forming apparatus. 'As shownlIl'Flg. l, such a gauge may comprise a stop plate 18 arrangedtransver'sely'to the/grid receiving chamberand atsuch distance from theguide 17 that the ends of the grid support wiresdwill touch the plate 18when the grid is approximately in its desire'dposition with respecttothe spreader rods-,9. The

gauge is preferably, adjustable, for example bymounting the plate 18 ona-threaded: rod

spect to the path of movement of said spread-- er rod. p 7

3. In apparatus for shaping grid electrodes from blanks comprisinghelical windings,

clamping means for encircling. the blank and provided with an apertureextending diametrically of a grid blank positioned in said clampingmeans, a spreader rod mounted to move in said aperture and through atleast a portion of a blank positioned in said clamp ing means, and aguide rib mounted on said clamping means to lie between adjacent turnssaid clamping means. p

4. In apparatus of the type stated, a frame carryinga pair of relativelymovable clamp- 7 ing arms, recesses on the opposed faces of said armscooperating to provlde a cyllndrlcal chamber for receiving a grid blankaper-.- tures through said arms and alined diametrically. ofsaidchamber, a spreader rod mount ed to moveaxially of" said apertures and Iacross saidchamber, and a guiderib on one of said arms for positioning agrid blank with respect to the path of movement of said rod. Intestimony whereof, I aflix my signature;

' AR'oLna; SNOW.

spreader rods maybe replaced by a shorter 1 rod which will enter onlyone side of the gridblank, or by a rod having a smaller diameter at'theportion which passes through one or both sides of the blank. v

While the illustrated apparatus shows two spreader rods, it will beapparent that'the invention is not restricted thereto as one or severalspreader rods may be employed. It

is therefore to be understoodthat various changes which may be made inthe several parts, theirrelative size, shape and location,

fall within the spirit of my invention as set V forth in the followingclaims.

Iclaim: I

In apparatus for shaping grid electrodes, cooperating members providingvacylindrical'chamber forreceiving and support- .ingja grid electrodeblank, spreader means slidable. diametrically of and through-saidchamberfand guide means on one of said members. for malntalmng apredetermined relation between a grld blank to be operated upon 'and'thepath of -movement of said spreader means. I v

2. In apparatus for forming'grld electrodes from helically woundblanks,'the com- I bination with supporting means for encircling ahelically wound grid electrode blank, and a movable spreader rod mountedto pass through a portion of ablank held in said sup porting means, of aguide rib positioned on said supporting meansto lie between adjacentturns of the helical winding of'the grid elecof the helical winding of agrid blank held in trode blank to position said blank with re-

